In a semiconductor device, a contact plug and/or a via plug are formed for interlayer connections between a semiconductor element and a wire, and between wires. The contact plug and the via plug are formed in such a manner as follows.
First, an element separation film and a semiconductor element are formed on a semiconductor substrate such as a silicon substrate, and an interlayer insulating film is further formed on the semiconductor element and the element separation film.
Next, the interlayer insulating film is selectively removed by means of mask patterning and etching, to form a via in the interlayer insulating film. Specifically, this formed via is a contact via for forming a contact plug to connect between a wire and a silicide layer on a diffusion layer and a gate electrode, or a plug via for forming a via plug to connect between a lower-layer wire and an upper-layer wire.
Then, a contact layer is formed on a side wall inside the via as thus formed for example by means of a PVD (Physical Vapor Deposition) technique. This contact layer has high adhesion both with a tungsten film and the interlayer insulating film, and is made of a titanium nitride film or the like, on which tungsten crystal nucleuses are apt to be generated as compared with on the interlayer insulating film. Further, the tungsten film is embedded into the via covered by the contact layer by means of a CVD (Chemical Vapor Deposition) technique. Thereafter, the contact layer and the tungsten film lying off the via are removed by means of a CMP (Chemical Mechanical Polishing) technique, to form the contact plug and the via plug.
As thus described, the tungsten film formed by means of the CVD technique has been long considered, and widely used to form plugs.